1. Field of the Invention
The present invention relates to an apparatus and method for generating sodium hypochlorite and/or chlorine gas from a brine solution in small quantities to be suitable and economical for backyard swimming pool use. The concept can also be expanded for larger commercial installations. The purpose of the invention is to replace the need to haul dangerous, toxic and poisonous chemicals from a store to the pool owner's home, store them where they might accidentally cause damage or loss of human life, and eliminate the need to continuously dispense these chemicals in uncertain proportions into the swimming pool.
2. Brief Description of the Prior Art
It is a well-known fact that for a swimming pool to be used safely the water must be sterile. In addition, if proper disinfectant or algaecide is not applied, the growth of algae will damage the pool surface and clog the pool filters. More often than not, the home swimming pool is a breeding ground for disease. Several current methods of chlorinating the home swimming pool are now in use.
One method is the adding of chlorine solution, normally a diluted solution of sodium hypochlorite. This is carried from the store in gallon bottles and dispensed manually by the user.
Another method is the use of powdered chlorine chemicals which may be added by hand or dispensed through a means of a hopper or supplied in stick form which slowly dissolves into the pool water either in a dispenser container or in some sort of floating element that rides on the pool surface.
Yet another method which is becoming more popular, even though it presents the greatest hazards, is the use of gas chlorine. Normally, a service company chlorinates the pool once a week by dispensing chlorine gas into the water and adding soda ash or some equivalent base to counteract the acid induced by the chlorine. Since the dispensing of the chlorine gas is done infrequently, i.e., once per week, the chlorine level is raised to a very high point at that time so that it will not drop below that required to maintain proper pool function within a week's time. This very high initial concentration of chlorine in the water adversely affects swimmer's tans and bleaches hair as well as bathing suits.
In all these instances, caustic chemicals must be transported to the pool site and in many cases bottled or boxed chemicals are left stored where they can be accidentally reached by children.
Many prior attempts have been made to generate the chlorine at the pool site. The most common of these utilize salt within the pool water itself and bypass a small portion of the filtered flow through an electrolysis cell which generates the chlorine. This prior system has not been satisfactory due to the continuous problem of the hardness minerals within the pool water precipitating and eventually clogging and damaging the cell. A number of methods have been employed by which this hardness could be removed through acid washing of the cell between pool use. However, this procedure requires complex automatic equipment or manual operation by the pool owner. In the former case, the equipment is too elaborate and complex to be practical for the home use application. In the latter case, the pool owner often as not would forget to operate the equipment and the cell would be destroyed. The problem is further compounded by the large amount of salt that has to be added to the pool water bringing the salinity content to the point where corrosion and electrolysis in the pool's plumbing system were often out of control.
Another objection to previous units is the amount of electricity required to operate the electrolysis cell since the salt concentration within the cell had to be kept low, usually less than 1%. A great deal of the electrical energy went into the production of hydrogen and oxygen, a wasteful by-product in this application. With the cost of energy steadily increasing, this method of production is simply not cost-effective.